Fossil tracks push back the invasion of land by 18 million years

marco_polo

The discovery of tetrapod footprints dated to 395 million years ago may have pushed back the date of the tetrapod land invasion by as much as 18 million years.

What is interesting about these dates is that it raises the possibility that rather than being novel innovators, the elpistostegids like Tiktaalik were more like late-surviving relatives that retained their fish like characteristics.

http://scienceblogs.com/notrocketscience/2010/01/fossil_tracks_push_back_the_invasion_of_land_by_18_million_y.php

Around 395 million years ago, a group of four-legged animals strode across a Polish coast. These large, amphibious creatures were among the first invaders of the land, the first animals with true legs that could walk across solid ground. With sprawling gaits and tails held high, they took pioneering footsteps. Their tracks eventually fossilised and their recent discovery yields a big surprise that could rewrite what we know about the invasion of land. These animals were walking around 18 million years earlier than expected.

The evolution of four-legged creatures - tetrapods - is one of the most evocative in life's history. It has been illustrated by a series of beautiful fossils that vividly show the transition from swimming with fins to walking on legs. These include Panderichthys, a fish with a large tetrapod-like head and a muscular pair of front fins. Tiktaalik expanded on these themes. Its head could turn about a solid neck. Its limbs had the fin rays of its fishy predecessors but clear wrist bones and basic fingers too. Tiktaalik could support itself on strong shoulder bones, bend its fins at the wrists, and splay out its hand-like bones.

Galvasean

I remember reading an article that suggested that the likes of Tiktaalic and Acanthostega appeared to be creatures which were already established land dwellers and were evolving toward water based lifestyles. This new discovery could potentially ad weight to the idea.
I'll try my best to find it.

marco_polo

Galvasean wrote: »

I remember reading an article that suggested that the likes of Tiktaalic and Acanthostega appeared to be creatures which were already established land dwellers and were evolving toward water based lifestyles. This new discovery could potentially ad weight to the idea.
I'll try my best to find it.

Cool if you can dig it out, that would certainly seem to be just as plausible a scenario given the timelines involved. And I would think that the scientists who proposed that theory would be pretty pleased with themselves after this discovery.